537684-22-3Relevant academic research and scientific papers
Divergent Coupling of Benzocyclobutenones with Indoles via C?H and C?C Activations
Bai, Jin-Hua,Lu, Hong,Wei, Hao,Xu, Peng-Fei,Ye, Dan,Zhao, Tian-Tian
, p. 23537 - 23543 (2020)
Highly selective divergent coupling reactions of benzocyclobutenones and indoles, in which the chemoselectivity is controlled by catalysts, are reported herein. The substrates undergo C2(indole)–C8(benzocyclobutenone) coupling to produce benzylated indoles and benzo[b]carbazoles in the Ni- and Ru-catalyzed reactions. A completely different selectivity pattern C2(indole)–C2(benzocyclobutenone) coupling to form arylated indoles is observed in the Rh-catalyzed reaction. Preliminary mechanistic studies suggest C?H and C?C activations in the reaction pathway. Synthetic utility of this protocol is demonstrated by the selective synthesis of three different types of carbazoles from the representative products.
One-Pot Asymmetric Oxidative Dearomatization of 2-Substituted Indoles by Merging Transition Metal Catalysis with Organocatalysis to Access C2-Tetrasubstituted Indolin-3-Ones
Zhao, Yong-Long,An, Jian-Xiong,Yang, Fen-Fen,Guan, Xiang,Fu, Xiao-Zhong,Li, Zong-Qin,Wang, Da-Peng,Zhou, Meng,Yang, Yuan-Yong,He, Bin
supporting information, p. 1277 - 1285 (2022/03/14)
A one-pot approach for the asymmetric synthesis of C2-tetrasubstituted indolin-3-ones from 2-substituted indoles was developed via merging transition metal catalysis with organocatalysis. This strategy involves two processes, including CuI catalyzed oxidative dearomatization of 2-substituted indoles using O2 as green oxidant, and followed by an proline-promoted asymmetric Mannich reaction with ketones or aldehydes. A series of C2-tetrasubstituted indolin-3-ones were obtained in 35–86% yields, 2:1->20:1 dr and 48–99% ee. Moreover, the synthetic 2-tetrasubstituted indolin-3-ones could be easily transformed into 1H-[1,3] oxazino [3,4-a]indol-5(3H)-ones via a [4+1] cyclization process. In addition, the synthetic compound 3 s show certain antibacterial activity against S. aureus ATCC25923 and multi-drug resistance bacterial strain of S. aureus (20151027077) and its MIC values up to 8 μg/mL and 16 μg/mL, respectively. (Figure presented.).
An iron(iii)-catalyzed dehydrogenative cross-coupling reaction of indoles with benzylamines to prepare 3-aminoindole derivatives
Chen, Wei-Li,Li, Kun,Liang, Cui,Liang, Wang-Fu,Liao, Wei-Cong,Mo, Dong-Liang,Qiu, Pei-Wen,Su, Gui-Fa
, p. 9610 - 9616 (2021/12/09)
We report a green cascade approach to prepare a variety of 3-aminoindole derivatives in good to excellent yields through an iron(iii)-catalyzed dehydrogenative cross-coupling reaction of 2-arylindoles and primary benzylamines under mild reaction conditions. Mechanistic studies show that a cascade reaction involves a tert-butyl nitrite (TBN)-mediated nitrosation of 2-substituted indoles and a 1,5-hydrogen shift to afford indolenine oximes, sequential iron(iii)-catalyzed condensation and a 1,5-hydrogen shift over four steps in a one-pot reaction. The reaction shows a broad substrate scope of indoles and benzylamines and tolerates a wide range of functional groups. Moreover, the reaction is easily performed at the gram scale without producing waste after the reaction is completed. The 3-aminoindole product is purified by simple extraction, washing, and recrystallization without flash column chromatography. A double imine ligand containing the 3-aminoindole unit is facile to obtain in a 52% yield in one step. The present method highlights readily available starting materials, a simple purification procedure, and the usage of cheap, nontoxic, and environmentally benign iron(iii) catalysts. This journal is
Pd/β-cyclodextrin-catalyzed C-H functionalization in water: A greener approach to regioselective arylation of (NH)-indoles with aryl bromides
Duan, Xin Hong,Xu, Peng
supporting information, p. 19425 - 19431 (2021/11/09)
A greener and more practical strategy for the site-selective C-H arylation of (NH)-indoles via coupling of (hetero)aryl bromides was developed, in which β-cyclodextrin, acting as both a ligand for Na2PdCl4 and a host for indoles, enables the reactions to occur easily in water. The key advantage of this method is the ingenious merging of aqueous homogeneous catalysis and ligand mediation, leading to the highly regioselective formation of C3-arylindoles with a broad substrate scope and functional-group tolerance. Moreover, the regioselectivity can be switched from the C3 to the C2-position by varying the nature of the base without recourse to employing ArI as substrates.
Aniline-initiated and Br?nsted acid-catalyzed one-pot reaction toward 2-aryl-3-sulfenylindoles by using α-aminocarbonyl compounds and primary amines with RSSR
Chen, De,Cheng, Chaozhihui,Deng, Wei,Guan, Wenjian,Liu, Yuxuan,Luo, Yongyue,Xiang, Jiannan,Zhang, Jiajia
, (2020/12/01)
A highly novel method of direct synthesis of 2-aryl-3-sulfenylindoles in moderate to good yields was developed via one-pot tandem reaction of readily available α-aminocarbonyl compounds and catalytic amount of benzenamines with RSSR.
Iminyl-radicals by electrochemical decarboxylation of α-imino-oxy acids: construction of indole-fused polycyclics
Wan, Jin-Lin,Cui, Jian-Feng,Zhong, Wei-Qiang,Huang, Jing-Mei
supporting information, p. 10242 - 10245 (2021/10/12)
Iminyl radicals are reactive intermediates that can be used for the construction of various valuable heterocycles. Herein, the electrochemical decarboxylation of α-imino-oxy acids for the generation of iminyl radicals has been accomplished under exogenous-oxidant- and metal-free conditions through the use ofnBu4NBr as a mediator. The resulting iminyl radicals undergo intramolecular cyclization smoothly with the adjacent (hetero)arenes to afford a series of indole-fused polycyclic compounds.
Iron-catalysed radical cyclization to synthesize germanium-substituted indolo[2,1-a]isoquinolin-6(5H)-ones and indolin-2-ones
Luo, Yani,Tian, Tian,Nishihara, Yasushi,Lv, Leiyang,Li, Zhiping
, p. 9276 - 9279 (2021/09/20)
A simple and efficient strategy for iron-catalysed cascade radical cyclization was developed, by which an array of germanium-substituted indolo[2,1-a]isoquinolin-6(5H)-ones and indolin-2-ones were obtained in one pot with germanium hydrides as radical precursors. A rapid intramolecular radical trapping mode enabled the selective arylgermylation of alkenes over the prevalent hydrogermylation reaction.
Regioselective Direct C2 Arylation of Indole, Benzothiophene and Benzofuran: Utilization of Reusable Pd NPs and NHC-Pd@MNPs Catalyst for C–H Activation Reaction
Hegde, Rajeev V.,Ong, Tiow-Gan,Ambre, Ram,Jadhav, Arvind H.,Patil, Siddappa A.,Dateer, Ramesh B.
, p. 1397 - 1405 (2020/10/02)
Abstract: A regioselective C2 arylation of indoles, benzothiophene and benzofuran without directing group has been accomplished using economically cheap Pd NPs and NHC-Pd@MNPs catalyst. The reusable catalyst is efficiently employed to access C2 arylated heterocycles in good to excellent yield. The reusability of the catalyst is studied up to five cycles and a gram-scale synthesis has been achieved. The reaction mechanism is well supported by control experiments and literature precedents. Grapic Abstract: [Figure not available: see fulltext.]
Chiral Br?nsted Acid from Chiral Phosphoric Acid Boron Complex and Water: Asymmetric Reduction of Indoles
Yang, Kai,Lou, Yixian,Wang, Chenglan,Qi, Liang-Wen,Fang, Tongchang,Zhang, Feng,Xu, Hetao,Zhou, Lu,Li, Wangyang,Zhang, Guan,Yu, Peiyuan,Song, Qiuling
, p. 3294 - 3299 (2020/01/21)
A new chiral Br?nsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This “designer acid catalyst”, which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3-protonation and hydride-transfer processes. Besides, bulky C2-alkyl-substituted N-unprotected indoles are also suitable for this system.
Pd-catalyzed C–H bond activation of Indoles for Suzuki reaction
Banerjee, Isita,Ghosh, Keshab Ch,Sinha, Surajit
, (2019/08/22)
Abstract: We present a practical method for Suzuki coupling by which unprotected or N-protected indoles may be selectively arylated in the C2-position through direct C–H bond activation by electrophilic Pd(TFA) 2 catalyst. The protocol is operationally simple as it is carried out in dioxane/water mixture, and air as the sole oxidant at room temperature. Various 2-arylated indoles were obtained in good yields. The protocol works for benzofuran, pyrrole and thiophene also. Graphic abstract: Selective C-2 arylation of heterocycles using Pd(II) catalyst via C–H activation was performed under ambient condition. C3–C2 migration of organopalladium intermediate controls the reaction pathway.[Figure not available: see fulltext.].
